Elongate medical device with distal cap

ABSTRACT

Elongate medical devices such as guidewires can be formed from a core wire and a preformed distal cap that is configured to fit over a distal end of the core wire. The distal cap can be attached using a variety of techniques. In particular, the distal cap can be attached to the core wire using laser welding.

TECHNICAL FIELD

The invention pertains generally to elongate medical devices such ascatheters, guidewires, and the like.

BACKGROUND

A wide variety of elongate medical devices such as catheters andguidewires have been developed. Such medical devices can be used tofacilitate navigation and treatment within the anatomy of a patient.Because the anatomy of a patient may be very tortuous, it can bedesirable to have particular performance features in an elongate medicaldevice. A number of different structures and assemblies for elongatemedical devices such as guidewires, catheters, and the like are known,each having certain advantages and disadvantages. There is an ongoingneed to provide alternative structures and assemblies.

SUMMARY OF SOME EMBODIMENTS

The invention provides several alternative designs, materials andmethods of manufacturing alternative medical device structures andassemblies.

Accordingly, an example embodiment of the invention can be found in anelongate medical device that includes an elongate shaft and a distal capthat is formed independently of the elongate shaft. A proximal end ofthe distal cap includes an aperture that can be configured to fit over adistal end of the elongate shaft. After the distal cap has been formed,it can be secured to the distal end of the elongate shaft.

Another example embodiment of the invention can be found in a guidewirethat can be produced by providing a core wire and a distal cap. Aproximal end of the distal cap can include an aperture that isconfigured to fit over a distal end of the core wire. The distal cap canbe positioned over the distal end of the core wire by inserting thedistal end of the core wire into the aperture, and then the distal capcan be attached to the distal end of the core wire.

Another example embodiment of the invention can be found in a guidewirethat has a core wire and an independently formed distal cap. A proximalend of the distal cap can include an aperture that can be configured toaccept the end of the core wire, and the distal cap can subsequently beattached to the distal end of the core wire.

Another example embodiment of the invention can be found in a method ofproducing a guidewire. A core wire can be provided, along with a distalcap. A proximal end of the distal cap can include an aperture that isconfigured to fit over a distal end of the core wire. The distal end ofthe core wire can be inserted into the distal cap aperture, and thedistal cap can be attached to the distal end of the core wire.

Another example embodiment of the invention can be found in a method ofproducing a guidewire. A core wire can be provided, along with a tubularsleeve. The tubular sleeve can be positioned over a distal end of thecore wire, and a metal ball can be positioned proximate a distal end ofthe tubular sleeve. At least a portion of the tubular sleeve and themetal ball can be melted via laser welding or plasma welding to form anatraumatic tip.

Another example embodiment of the invention can be found in a guidewirethat includes a core wire and a distal cap. A proximal end of the distalcap can include a tubular structure that defines a lumen that isconfigured to fit over a distal end of the core wire. A distal end ofthe distal cap can define an arcuate atraumatic surface. The distal capcan be formed independently of the core wire and can be attached to thecore wire by inserting the distal end of the core wire into the lumenand attaching the distal cap to the core wire.

Another example embodiment of the invention can be found in a guidewirethat includes a core wire and means of providing a distal tip to thecore wire, the means being formed independently and subsequently securedto a distal end of the core wire.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present invention.The Figures, and Detailed Description which follow more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE FIGURES

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a partially sectioned side view of a distal portion of aguidewire core wire in accordance with one example embodiment of theinvention, showing a profile in which a distal portion includes severaltapers and a distal-most widened diameter portion;

FIG. 2 is a perspective view of a distal cap in accordance with oneexample embodiment of the invention;

FIG. 3 is a cross-sectional view of the distal cap of FIG. 2, takenalong line 3—3;

FIG. 4 is a partially sectioned side view of the guidewire core wire ofFIG. 1, with the addition of a coil and the distal cap of FIG. 2;

FIG. 5 is a partially sectioned side view of the guidewire constructionof FIG. 4, with the addition of a polymer sleeve or sheath;

FIG. 6 is a partially sectioned side view of another example guidewireconstruction having a polymer sheath;

FIG. 7 is a partially sectioned side view of another example guidewireconstruction, showing an alternative tip configuration;

FIG. 8 is a partially sectioned side view of another example guidewireconstruction, showing an alternate distal cap design;

FIG. 9 is a partially sectioned side view of another example guidewireconstruction, showing an alternative tip configuration;

FIG. 10 is a partially sectioned side view of another example guidewireconstruction, showing an alternative tip configuration prior to formingthe atraumatic portion;

FIG. 11 is a partially sectioned side view of the guidewire constructionof FIG. 10, shown after the forming of the atraumatic portion;

FIG. 12 is a partially sectioned side view of another example guidewireconstruction showing an alternative tip configuration prior to formingthe atraumatic portion;

FIG. 13 is a partially sectioned side view of the guidewire constructionof FIG. 12, shown after the forming of the atraumatic portion;

FIG. 14 is a cross-sectional exploded view of some of the components ofanother example medical device;

FIG. 15 is a cross-sectional side view depicting the device shown inFIG. 14 partially assembled;

FIG. 16 is a cross-sectional side view of the example medical device ofFIGS. 14 and 15 including a covering; and

FIG. 17 is a cross-sectional side view of another example medicaldevice.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following description should be read with reference to the drawingswherein like reference numerals indicate like elements throughout theseveral views. The drawings, which are not necessarily to scale, depictillustrative but non-limiting embodiments of the claimed invention.

For example, although discussed with specific reference to guidewires inthe particular embodiments described herein, the invention may beapplicable to a variety of medical devices that are adapted to beadvanced into the anatomy of a patient through an opening or lumen. Forexample, the invention may be applicable to fixed wire devices,catheters (e.g. balloon, stent delivery, etc.) drive shafts forrotational devices such as atherectomy catheters and IVUS catheters,endoscopic devices, laproscopic devices, embolic protection devices,spinal or cranial navigational devices, and other such devices.

Refer now to FIGS. 1–4, which illustrate components of one exampleembodiment of a guidewire including a core wire 10, a distal cap 30connected to the distal end of the core wire 10 and other structure suchas a coil. FIG. 1 illustrates a distal portion of a guidewire core wire10 that has a distal end 12 and a proximal end 14.

As shown, the core wire 10 has a proximal constant diameter section 16,an intermediate constant diameter section 20 and a distal constantdiameter section 24. A proximal taper section 18 adjoins the proximalconstant diameter section 16 and the intermediate constant diametersection 20. An intermediate taper section 22 adjoins the intermediateconstant diameter section 20 and the distal constant diameter section24. In some embodiments, the constant diameter section 24, or a portionthereof, can be formed into a ribbon to enhance lateral flexibility.

The core wire 10 also has a widened diameter portion 28 that ispositioned at the distal end 12 of the core wire 10 and that adjoins adistal taper section 26 that is positioned between the widened diameterportion 28 and the distal constant diameter section 24. The wideneddiameter portion 28 can act as a heat sink in certain embodiments thatuse certain attachment techniques using heat to attach the distal cap30, as discussed below, but this is not necessary.

One of skill will recognize that a guidewire core wire can have aprofile different from that illustrated in FIG. 1. For example, the corewire 10 can be continuously tapered, can have a tapered section or anumber or series of tapered sections of differing diameters, or can havea constant diameter. In some embodiments, the core wire 10 can betapered or otherwise formed to have a geometry that decreases in crosssectional area toward the distal end thereof. If tapered, the core wire10 can include a uniform or a nonuniform transition between thesections, depending on the transition characteristics desired. Forexample, the core wire 10 can be linearly tapered, tapered in acurvilinear fashion, or tapered in a step-wise fashion. The angle of anysuch tapers can vary, depending upon the desired flexibilitycharacteristics. The length of the taper may be selected to obtain amore (longer length) or less (shorter length) gradual transition instiffness.

The structure used to construct the core wire 10 can be designed suchthat a proximal portion 13 is relatively stiff for pushability andtorqueability, and a distal portion 11 is relatively flexible bycomparison for better lateral trackability and steerability. Forexample, in some embodiments, the proximal portion 13 has a constant orgenerally uniform diameter along its length to enhance stiffness.However, embodiments in which the proximal portion 13 has a taperedportion or a series of tapered portions are also contemplated. Thediameter of the proximal portion 13 can be sized appropriately for thedesired stiffness characteristics dependent upon the material used. Forexample, in some embodiments, the proximal portion 13 can have adiameter in the range of about 0.010 to about 0.025 inches or greater,and in some embodiments, in the range of about 0.010 to about 0.018inches or greater.

The distal portion 11 can likewise be constant diameter, can becontinuously tapered, or can have a tapered section or a number or aseries of tapered sections of differing diameters. In embodiments wherethe structure of core wire 10 is designed such that the distal portion11 is relatively flexible by comparison to the proximal portion 13, thedistal portion 11 can include at least one tapered or reduced diameterportion for better flexibility characteristics.

The tapered and constant diameter portions can be formed by any one of anumber of different techniques, for example, by centerless grinding,stamping and the like. A centerless grinding technique can utilize anindexing system employing sensors (e.g., optical/reflective, magnetic)to avoid excessive grinding. In addition, the centerless grindingtechnique can utilize a CBN or diamond abrasive grinding wheel that iswell shaped and dressed to avoid grabbing the core wire 10 during thegrinding process. Moreover, some stamping techniques can be used to forma portion of the guidewire, for example, a distal portion, into a ribbonor other like structure.

The lengths of the proximal and distal portions 13, 11 are typicallydictated by the length and flexibility characteristics desired in thefinal medical device. In some embodiments, the proximal portion 13 canhave a length in the range of about 50 to about 300 centimeters, and thedistal portion 11 can have a length in the range of about 3 to about 50centimeters.

The core wire 10 can have a solid cross-section as shown, but in someembodiments, can have a hollow cross-section. In yet other embodiments,core wire 10 can include a combination of areas having solidcross-sections and hollow cross sections.

In some embodiments, the core wire 10 can be formed of any suitablemetallic, polymeric or composite material. In some embodiments, part orall of the core wire 10 can be formed of a metal or a metal alloy. Someexamples of suitable metals and metal alloys include stainless steel,such as 304V, 304 L, and 316 L stainless steel; alloys includingnickel-titanium alloy such as linear elastic or superelastic (i.e.pseudoelastic) nitinol; nickel-chromium alloy; nickel-chromium-ironalloy; cobalt alloy; tungsten or tungsten alloys; MP35-N (having acomposition of about 35% Ni, 35% Co, 20% Cr, 9.75% Mo, a maximum 1% Fe,a maximum 1% Ti, a maximum 0.25% C, a maximum 0.15% Mn, and a maximum0.15% Si); hastelloy; monel 400; inconel 625; or the like; or othersuitable material. The particular material used can be chosen in partbased on the desired flexibility requirements of the core wire 10. Insome particular embodiments, the core wire 10 can be formed from asuperelastic or linear elastic nickel-titanium alloy, for example,linear elastic or superelastic (i.e. pseudoelastic) nitinol.

The word nitinol was coined by a group of researchers at the UnitedStates Naval Ordinance Laboratory (NOL) who were the first to observethe shape memory behavior of this material. The word nitinol is anacronym including the chemical symbol for nickel (Ni), the chemicalsymbol for titanium (Ti), and an acronym identifying the Naval OrdinanceLaboratory (NOL).

Within the family of commercially available nitinol alloys, is acategory designated “linear elastic” which, although is similar inchemistry to conventional shape memory and superelastic varieties,exhibits distinct and useful mechanical properties. By skilledapplications of cold work, directional stress, and heat treatment, thewire is fabricated in such a way that it does not display a substantial“superelastic plateau” or “flag region” in its stress/strain curve.Instead, as recoverable strain increases, the stress continues toincrease in an essentially linear relationship until plastic deformationbegins. In some embodiments, the linear elastic nickel-titanium alloy isan alloy that does not show any martensite/austenite phase changes thatare detectable by DSC and DMTA analysis over a large temperature range.

For example, in some embodiments, there is no martensite/austenite phasechanges detectable by DSC and DMTA analysis in the range of about −60°C. to about 120° C. The mechanical bending properties of such materialare therefore generally inert to the effect of temperature over thisvery broad range of temperature. In some particular embodiments, themechanical properties of the alloy at ambient or room temperature aresubstantially the same as the mechanical properties at body temperature.In some embodiments, the use of the linear elastic nickel-titanium alloyallows the guidewire to exhibit superior “pushability” around tortuousanatomy.

In some embodiments, the linear elastic nickel-titanium alloy is in therange of about 50 to about 60 weight percent nickel, with the remainderbeing essentially titanium. In some particular embodiments, thecomposition is in the range of about 54 to about 57 weight percentnickel. One example of a suitable nickel-titanium alloy is FHP-NT alloycommercially available from Furukawa Techno Material Co. of Kanagawa,Japan. Some examples of nickel-titanium alloys include those disclosedin U.S. Pat. Nos. 5,238,004 and 6,508,803, which are incorporated hereinby reference. In some other embodiments, a superelastic alloy, forexample a superelastic nitinol can be used to achieve desiredproperties.

In at least some embodiments, portions or all of the core wire 10, orother structures included within the medical device may also be dopedwith, made of, or otherwise include a radiopaque material. Radiopaquematerials are understood to be materials capable of producing arelatively bright image on a fluoroscopy screen or another imagingtechnique during a medical procedure. This relatively bright image aidsthe user of device in determining its location. Some examples ofradiopaque materials can include, but are not limited to, gold,platinum, palladium, tantalum, tungsten alloy, polymer material loadedwith a radiopaque filler, and the like.

In some embodiments, a degree of MRI compatibility can be imparted. Forexample, to enhance compatibility with Magnetic Resonance Imaging (MRI)machines, it may be desirable to make the core wire 10, or otherportions thereof, in a manner that would impart a degree of MRIcompatibility. For example, the core wire 10, or portions thereof, maybe made of a material that does not substantially distort the image andcreate substantial artifacts (artifacts are gaps in the image). Certainferromagnetic materials, for example, may not be suitable because theymay create artifacts in an MRI image. Core wire 10, or portions thereof,may also be made from a material that the MRI machine can image. Somematerials that exhibit these characteristics include, for example,tungsten, Elgiloy, MP35N, nitinol, and the like, and others.

The entire core wire 10 can be made of the same material, or in someembodiments, can include portions or sections that are made of differentmaterials. In some embodiments, the material used to construct differentportions of the core wire 10 can be chosen to impart varying flexibilityand stiffness characteristics to different portions of the wire. Forexample, the proximal portion 13 and the distal portion 11 can be formedof different materials (i.e., materials having different moduli ofelasticity) resulting in a difference in flexibility. In someembodiments, the material used to construct the proximal portion 13 canbe relatively stiff for pushability and torqueability, and the materialused to construct the distal portion 11 can be relatively flexible bycomparison for better lateral trackability and steerability. Forexample, the proximal portion 13 can be formed of, for example,straightened 304v stainless steel wire, and the distal portion 11 can beformed of, for example, a straightened super elastic or linear elasticalloy (e.g., nickel-titanium) wire.

In embodiments where different portions of core wire 10 are made ofdifferent material, the different portions can be connected using anysuitable connecting techniques. For example, the different portions ofthe core wire can be connected using welding, soldering, brazing,adhesive, or the like, or combinations thereof. Additionally, someembodiments can include one or more mechanical connectors or connectorassemblies to connect the different portions of the core wire that aremade of different materials. The connector can include any structuregenerally suitable for connecting portions of a guidewire. One exampleof a suitable structure includes a structure such as a hypotube or acoiled wire which has an inside diameter sized appropriately to receiveand connect the different portions of the core wire. Some methods andstructures that can be used to interconnect different shaft sections aredisclosed in U.S. patent application Ser. Nos. 09/972,276, and10/086,992, which are incorporated herein by reference. Additionally,some methods and structures using expandable alloys to connect guidewiremembers are disclosed in U.S. patent application Ser. No. 10/375,766.Additionally, some methods and structures including alternativesstructures for connecting medical device sections are disclosed in aU.S. patent application Ser. No. 10/375,493, which is incorporatedherein by reference.

It is to be understood that a broad variety of materials, dimensions andstructures can be used to construct suitable embodiments, depending onthe desired characteristics. The following examples of some dimensionsare included by way of example only, and are not intended to belimiting.

In some embodiments, the core wire 10 can have the general profile setforth in FIG. 1. In some example embodiments, the proximal constantdiameter section 16 can have a length that is in the range of about 10to 120 inches and a diameter that is in the range of about 0.010 toabout 0.040 inches. The intermediate constant diameter section 20 canhave a length that is in the range of about 2 to about 12 inches and adiameter that is in the range of about 0.007 to about 0.025 inches. Thedistal constant diameter section 24 can have a length that is in therange of about 1 to about 4 inches and a diameter that is in the rangeof about 0.002 to about 0.004 inches. The heat sink portion 28 can havea length that is in the range of about 0.025 to about 0.25 inches and adiameter that is in the range of about 0.005 to about 0.20 inches. Theproximal taper section 18, the intermediate taper section 22 and thedistal taper section 26 can each have a length that is in the range ofabout 0.5 to about 4 inches.

FIGS. 2 and 3 illustrate an embodiment of a distal cap 30 that isadapted and configured to fit over the distal end 12 of the core wire10. FIG. 2 is a perspective view of the distal cap 30 while FIG. 3 is across-sectional view. The distal cap 30 has a proximal end 32 and adistal end 34. The distal end 34 can be configured to provide anatraumatic tip once the distal cap 30 has been secured to the core wire10 (as discussed hereinafter). In some embodiments, as illustrated, thedistal end 34 of the distal cap 30 can have a hemisphericalconfiguration.

The proximal end 32 of the distal cap 30 can be adapted and configuredto interact with the distal end 12 of the core wire 10. In someembodiments, the proximal end 32 of the distal cap 30 is configured suchthat the distal end 12 of the core wire 10 can fit at least partiallyinside the distal cap 30. In some embodiments, the proximal end 32 ofthe distal cap 30 can include a lumen or aperture 36 that extends atleast partially into the distal cap 30 and that is surrounded by a shell38. The shell 38 can in some embodiments have an annular or tubularform.

In some illustrative but, non-limiting embodiments, the distal cap 30can have a proximal portion that is substantially cylindrical in shape,with an outer diameter in the range of about 0.010 to about 0.040 inchesand a length that is in the range of about 0.025 to about 0.250 inches.The aperture 36 can have an inner diameter that is in the range of about0.002 to about 0.150 inches and a depth that is in the range of about0.010 to about 0.150 inches.

The distal cap 30 can be formed from a variety of different materials,depending on desired performance characteristics. Suitable materials caninclude polymers, metals and metal alloys, such as those discussed withrespect to the core wire 10, as well as other materials such ascomposites, amorphous or polycrystalline inorganics, and carbons such aspyrolitic carbon. Some illustrative but non-limiting examples ofsuitable metals and metal alloys include stainless steel,nickel-titanium alloys, nickel-chromium alloys, nickel-chromium-ironalloy, cobalt alloy, tungsten or tungsten alloys, Inconel 625, and othersuitable materials.

In at least some embodiments, portions or all of the distal cap 30 canbe doped with, made of, or otherwise include a radiopaque material, asdiscussed with respect to the core wire 10. Some examples of radiopaquematerials can include, but are not limited to, gold, platinum,palladium, tantalum, tungsten alloy, polymer material loaded with aradiopaque filler, and the like.

In some embodiments, a degree of MRI compatibility can be imparted. Forexample, to enhance compatibility with Magnetic Resonance Imaging (MRI)machines, it can be desirable to make the distal cap 30 in a manner thatwould impart a degree of MRI compatibility, as discussed with respect tothe core wire 10. Some suitable materials include, for example,tungsten, Elgiloy, MP35N, nitinol, and the like, and others.

In some embodiments, the distal cap 30 can be formed of a material suchas a metallic material that is amenable, for a particular attachmentmethod, to being welded to the distal end 12 of the core wire 10, aswill be discussed in greater detail hereinafter. In some particularembodiments, it can be beneficial but not necessary for the distal cap30 to be formed of the same metal or metal alloy as the distal end 12 ofthe core wire 1O.

For example, if the core wire 10 is formed of stainless steel, it can bebeneficial for the distal cap 30 to be formed of stainless steel or amaterial compatible therewith. In other embodiments, both of the distalcap 30 and the distal end 12 of the core wire 10 can be formed of thesame metal alloy, such as nitinol.

A variety of different processes, such as deep drawing, roll forming ormetal stamping can be used to form the distal cap 30. In someembodiments, the distal cap 30 can be metal injection molded. It iscontemplated that the distal cap 30 can be formed via a casting process,with the aperture 36 formed through a drilling process. In someembodiments, the distal cap 30 can be formed using processes such asimpact extrusion, cold forming or electrodeposition.

FIG. 4 illustrates one example embodiment of a guidewire 52 includingthe distal cap 30 in position over the distal end 12 of the core wire10. In some embodiments, the distal cap 30 can be positioned such thatits proximal end 32 overlaps a portion of the heat sink 28. Asillustrated, the distal cap 30 extends proximally such that the proximalend 32 of the distal cap 30 is positioned at a midpoint 40 that isapproximately midway between the distal end 42 of the heat sink 28 andthe proximal end 44 thereof. In other embodiments, the proximal end 32can extend further proximally on the core wire 10, or may end at a moredistal portion on the core wire 10.

A coil 46 having a distal end 48 and a proximal end 50 is positionedsuch that the distal end 48 of the coil 46 overlaps a portion of theheat sink 28. In some embodiments, the distal end 48 of the coil 46 canbe positioned proximate the midpoint 40 and thus can be positionedproximate the proximal end 32 of the distal cap 30. The proximal end 50of the coil 46 can in some embodiments be positioned proximate theproximal taper section 18. One of skill will recognize that the coil 46can be positioned such that its proximal end 50 is proximate theintermediate taper section 22, or that a guidewire can include both acoil 46 as illustrated and one or more additional coils, for example,disposed about or under the coil 46.

The coil 46 can be formed of a variety of materials including metals,metal alloys, polymers, and the like. Some examples of material for usein the coil include stainless steel, such as 304V, 304 L and 316 Lstainless steel, nickel-chromium alloy, nickel-chromium-iron alloy,cobalt alloy, tungsten or tungsten alloys, MP35-N, Hastelloy, Monel 400,Inconel 625, or other suitable materials.

Some additional examples of suitable material include straightened superelastic, i.e. pseudoelastic, or linear elastic alloy (e.g.,nickel-titanium) wire, or alternatively, a polymer material, such as ahigh performance polymer. In some embodiments, the coil 46 or portionsthereof can be made of or include or be coated with a radiopaquematerial such as gold, platinum, tungsten, or the like, or alloysthereof. In some embodiments, the coil 46 can be made of a material thatis compatible with the core wire 10 and the distal cap 30.

In some embodiments, it can be advantageous for the coil 46 to includeradiopaque materials, as discussed with respect to the core wire 10.Some examples of radiopaque materials can include, but are not limitedto, gold, platinum, palladium, tantalum, tungsten alloy, polymermaterial loaded with a radiopaque filler, and the like.

In some embodiments, a degree of MRI compatibility can be imparted. Forexample, to enhance compatibility with Magnetic Resonance Imaging (MRI)machines, it can be desirable to make the coil 46 in a manner that wouldimpart a degree of MRI compatibility, as discussed with respect to thecore wire 10. Some suitable materials include, for example, tungsten,Elgiloy, MP35N, nitinol, and the like, and others.

The coil 46 can be formed of round or flat ribbon ranging in dimensionsto achieve desired characteristics, such as flexibility. A round ribboncan be considered as having a round or oval cross-sectional shape whilea flat ribbon can be considered as having a rectangular cross-sectionalshape. In some embodiments, the coil 46 can be a round ribbon in therange of about 0.0005–0.004 inches in diameter, and can have a length inthe range of about 0.1 to about 20 inches, however, other dimensions arecontemplated.

The coil 46 can be wrapped in a helical fashion by conventional windingtechniques. The pitch of adjacent turns of the coil 46 may be tightlywrapped so that each turn touches the succeeding turn or the pitch maybe set such that the coil 46 is wrapped in an open fashion.

To form the guidewire assembly 52 shown in FIG. 4, the distal cap 30 andthe coil 46 can be positioned proximate the core wire 10 as illustrated.The distal cap 30 and the coil 46 can be secured to the core wire 10 inany suitable manner, including for example welding, soldering, brazing,crimping, friction fitting, adhesive bonding, mechanical interlockingand the like. In these and some other example embodiments, securing thedistal cap 30 to the core wire 10 may include the use of a connectorand/or an expandable alloy, for example a bismuth alloy. Some examplesof methods, techniques, and structures that can be used to interconnectdifferent portions of a guidewire are disclosed in U.S. patentapplication Ser. No. 375,766 which is hereby incorporated by reference,and in U.S. patent application Ser. Nos. 09/972,276 and 10/086,992,which are incorporated herein by reference.

In some embodiments, the coil 46 and the cap 30 are welded to the corewire 10. It is to be appreciated that various welding processes can beutilized. In general, welding refers to a process in which two materialssuch as metal or metal alloys are joined together by heating the twomaterials sufficiently to at least partially melt adjoining surfaces ofeach material. A variety of heat sources can be used to melt theadjoining materials. Examples of welding processes that can be suitablein some embodiments include LASER welding, resistance welding, TIGwelding, microplasma welding, electron beam, and friction or inertiawelding.

LASER welding equipment that may be suitable in some embodiments iscommercially available from Unitek Miyachi of Monrovia, Calif. andRofin-Sinar Incorporated of Plymouth, Mich. Resistance welding equipmentthat may be useful in some embodiments is commercially available fromPalomar Products Incorporated of Carlsbad, Calif. and PolarisElectronics of Olathe, Kans. TIG welding equipment that may be useful insome embodiments is commercially available from Weldlogic Incorporatedof Newbury Park, Calif. Microplasma welding equipment that may be usefulin some embodiments is commercially available from Process WeldingSystems Incorporated of Smyrna, Tenn.

In some embodiments, laser or plasma welding can be used to secure thedistal cap 30, the coil 46 and the core wire 10 securely together. Inlaser welding, a light beam is used to supply the necessary heat. Laserwelding can be beneficial in the processes contemplated by theinvention, as the use of a laser light heat source can provide pinpointaccuracy. In some embodiments, laser diode soldering can be useful,again for pinpoint accuracy. Further, securing the distal cap 30, coil46, and the core wire 10 together may include the use of expandablealloys (e.g., bismuth alloys) similar to what is described above.

FIG. 5 shows an alternative guidewire assembly with an optional polymersleeve 54 while FIG. 6 shows an alternative guidewire assembly having apolymer sheath 53. In this embodiment, no coil is included. Instead, apolymer tip guidewire is formed by including the polymer sheath 53 thatforms a rounded tip over the distal cap 30. The polymer sheath 53 orpolymer sleeve 54 can be made from any material that can provide thedesired strength, flexibility or other desired characteristics. Thesheath 53 or polymer sleeve 54 can in some non-limiting embodiments havea length that is in the range of about 3 to about 15 inches and can havean inner diameter that is in the range of about 0.002 to about 0.025inches and an outer diameter that is in the range of about 0.010 toabout 0.040 inches.

The use of a polymer can serve several functions, such as improving theflexibility properties of the guidewire assembly. Choice of polymers forthe sleeve 53 or sheath 54 will vary the flexibility. For example,polymers with a low durometer or hardness will make a very flexible orfloppy tip. Conversely, polymers with a high durometer will make a tipwhich is stiffer. The use of polymers for the sleeve can also provide amore atraumatic tip for the guidewire. An atraumatic tip is bettersuited for passing through fragile body passages. Finally, a polymer canact as a binder for radiopaque materials, as discussed in more detailbelow.

Some suitable materials include polymers, and like material. Examples ofsuitable polymer material include any of a broad variety of polymersgenerally known for use as guidewire polymer sleeves. In someembodiments, the polymer material used is a thermoplastic polymermaterial. Some examples of some suitable materials include polyurethane,elastomeric polyamides, block polyamide/ethers (such as Pebax),silicones, and co-polymers. The sleeve may be a single polymer, multiplelayers, or a blend of polymers. By employing careful selection ofmaterials and processing techniques, thermoplastic, solvent soluble, andthermosetting variants of these materials can be employed to achieve thedesired results.

Further examples of suitable polymeric materials include but are notlimited to poly(L-lactide) (PLLA), poly(D,L-lactide) (PLA),polyglycolide (PGA), poly(L-lactide-co-D,L-lactide) (PLLA/PLA),poly(L-lactide-co-glycolide) (PLLA/PGA), poly(D, L-lactide-co-glycolide)(PLA/PGA), poly(glycolide-co-trimethylene carbonate) (PGA/PTMC),polyethylene oxide (PEO), polydioxanone (PDS), polycaprolactone (PCL),polyhydroxylbutyrate (PHBT), poly(phosphazene), polyD,L-lactide-co-caprolactone) (PLA/PCL), poly(glycolide-co-caprolactone)(PGA/PCL), polyanhydrides (PAN), poly(ortho esters), poly(phosphateester), poly(amino acid), poly(hydroxy butyrate), polyacrylate,polyacrylamid, poly(hydroxyethyl methacrylate), polyurethane,polysiloxane and their copolymers.

In some embodiments, the sheath 53, sleeve 54, or portions thereof, caninclude, or be doped with, radiopaque material to make the sheath 53,sleeve 54, or portions thereof, more visible when using certain imagingtechniques, for example, fluoroscopy techniques. Any suitable radiopaquematerial known in the art can be used. Some examples include preciousmetals, tungsten, barium subcarbonate powder, and the like, and mixturesthereof. In some embodiments, the polymer can include different sectionshaving different amounts of loading with radiopaque material. Forexample, the sheath 53 or sleeve 54 can include a distal section havinga higher level of radiopaque material loading, and a proximal sectionhaving a correspondingly lower level of loading.

In some embodiments, it is also contemplated that a separate radiopaquemember or a series of radiopaque members, such as radiopaque coils,bands, tubes, or other such structures could be attached to theguidewire core wire 10, or incorporated into the core wire by plating,drawing, forging, or ion implantation techniques.

The sheath 53 or sleeve 54 can be disposed around and attached to theguidewire assembly 52 using any suitable technique for the particularmaterial used. In some embodiments, the sheath 53 or sleeve 54 can beattached by heating a sleeve of polymer material to a temperature untilit is reformed around the guidewire assembly 52. In some embodiments,the sheath 53 or the sleeve 54 can be secured to the core wire 10 usinga suitable adhesive. In some other embodiments, the sheath 53 or sleeve54 can be attached using heat shrinking techniques. In otherembodiments, the sheath 53 or sleeve 54 can be co-extruded with the corewire 10. The sleeve 54 can be finished, for example, by a centerlessgrinding or other method, to provide the desired diameter and to providea smooth outer surface.

A guidewire in accordance with some embodiments of the invention canoptionally include a coating layer such as a lubricious coating layerover part or all of the guidewire assembly 52 or even over part or allof the polymer sheath 53 or sleeve 54. Hydrophobic coatings such asfluoropolymers provide a dry lubricity which improves guide wirehandling and device exchanges. Lubricious coatings improve steerabilityand improve lesion crossing capability. Suitable lubricious polymers arewell known in the art and may include hydrophilic polymers such aspolyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxyalkyl cellulosics, algins, saccharides, caprolactones, and the like, andmixtures and combinations thereof. Hydrophilic polymers may be blendedamong themselves or with formulated amounts of water insoluble compounds(including some polymers) to yield coatings with suitable lubricity,bonding, and solubility. In some embodiments, the more distal portion ofthe guidewire is coated with a hydrophilic polymer as discussed above,and the more proximal portions is coated with a fluoropolymer, such aspolytetrafluroethylene (PTFE).

FIGS. 7 through 13 illustrate other example embodiments of theinvention. FIGS. 7–9, for example, shows alternate embodiments in whicha core wire 56 has, in sequence, a proximal constant diameter section58, an adjoining proximal taper section 60, an intermediate constantdiameter section 62, an adjoining distal taper section 64 and a distalconstant diameter section 66. Unlike the core wire 10 of the previousFIGS., the core wire 56 has no enlarged portion or heat sink at thedistal end thereof. The core wire 56 can be manufactured from anysuitable material, such as the metals and metal alloys discussed withrespect to the core wire 10. FIGS. 7, 8 and 9 each illustrate particularembodiments of providing and securing a distal cap to the core wire 56.

In FIG. 7, a coil 70 is positioned over the distal constant diametersection 66. The coil 70 has a distal end 72 that can be positionedproximate a distal end 68 of the distal constant diameter section 66 anda proximal end 74 that can be positioned proximate the distal tapersection 74. One of skill will recognize that the proximal end 74 of thecoil 70 could extend further in a proximal direction, depending on theexact profile of the core wire 56. The coil 70 can be manufactured usingthe materials and parameters previously discussed with respect to thecoil 46.

In this illustrative embodiment, a distal cap 76 having a distal end 78and a proximal end 80 is adapted and configured to fit over the distalend 68 of the distal constant diameter section 66. In particular, theproximal end 80 of the distal cap 76 includes an aperture 82 that issized and configured to accept the distal end 68 of the distal constantdiameter section 66 as well as the distal end 72 of the coil 70. Thedistal cap 76 can be manufactured using similar materials and proceduresas previously discussed with respect to the distal cap 30.

The distal cap 76 and the coil 70 can be secured to the core wire 56 inany suitable manner, including those described above, for examplewelding, soldering, brazing, crimping, friction fitting, adhesivebonding and the like. In some embodiments, laser or plasma welding canbe used to secure the distal cap 76, the coil 70 and the core wire 56securely together. Additionally, securing the distal cap 76, the coil70, and the core wire 56 may include the use of expandable alloys (e.g.,bismuth alloys) similar to what is described above.

In the embodiment shown in FIG. 7, the guidewire includes a polymericlayer 55. It is to be understood that the guidewire can include one ormore additional polymeric layers as discussed previously. Moreover, sucha guidewire can be partially or completely coated with a lubricious orhydrophilic coating as described hereinabove.

In FIG. 8, a distal sleeve 84 having a distal end 86 and a proximal end88 is positioned over the distal constant diameter section 66 of thecore wire 56. The distal sleeve 84 can be positioned such that thedistal end 86 of the distal sleeve 84 is proximate the distal end 68 ofthe core wire 56. The distal sleeve 84 can be formed of any suitablematerial, such as the metals and metal alloys previously discussed.

As illustrated, the distal sleeve 84 can have an outer diameter thatapproximates an outer diameter of the intermediate constant diametersection 62. As a result, a coil 90 having a distal end 92 and a proximalend 94 can be positioned such that the distal end 92 of the coil 90 isproximate a midpoint of the distal sleeve 84 and the proximal end 94 ofthe coil 90 is proximate the distal taper section 60. The coil 90 can bemanufactured as discussed for example with respect to the coil 46.

A distal cap 96 has a distal end 98 and a proximal end 100. In someembodiments, the distal end 98 of the distal cap 96 can form anatraumatic tip and can in particular embodiments form a hemisphericalshape. In some embodiments, the proximal end 100 of the distal cap 96can be configured to fit securely over the distal end 68 of the corewire 56 and the distal end 86 of the distal sleeve 84. In particular,the proximal end 100 of the distal cap 96 can include an aperture 102that is sized to fit securely over the distal end 86 of the distalsleeve 84. The distal cap 96 can be manufactured as previously discussedwith respect to the distal cap 30.

In the embodiment shown in FIG. 8, it is to be understood that such aguidewire can include one or more polymeric layers as discussedpreviously and may or may not include a coil 90 as shown. Moreover, sucha guidewire can be partially or completely coated with a lubricious orhydrophilic coating as described hereinabove.

FIG. 9 shows a core wire 56 and coil 90 as described in relation to theprevious Figures. A distal cap 104 has a distal end 106 and a proximalend 108. In some embodiments, the distal end 106 of the distal cap 104can form an atraumatic tip and can in particular embodiments form ahemispherical shape. The proximal end 108 of the distal cap 104 can beconfigured to fit over the distal end 68 of the core wire 56. The distalcap 104 can be manufactured as previously discussed with respect to thedistal cap 30.

In some embodiments, the proximal end 108 of the distal cap 104 caninclude an aperture 110 that is configured to accept the distal end 68of the core wire 56. In particular, the aperture 110 can have an innerdiameter that approximates an outer diameter of the core wire 56 and adepth that is sufficient to permit the distal end 68 of the core wire 56to penetrate the distal cap 104. The proximal end 108 of the distal cap104 can also include a shoulder 112 that can be configured to accept thedistal end 92 of the coil 90.

Once the distal cap 104 has been positioned over the core wire 56 andunder the coil 90, the distal cap 104 and the coil 90 can be secured tothe core wire 56 in any suitable manner, including for example welding,soldering, brazing, crimping, friction fitting, adhesive bonding and thelike or other technique, for example those described above in relationto method of the distal cap. In some embodiments, laser or plasmawelding can be used to secure the distal cap 104, the coil 90 and thecore wire 56 securely together.

In the embodiment shown in FIG. 9, it is to be understood that such aguidewire can include one or more polymeric layers as discussedpreviously. Additionally, in some embodiments, a coil is not used, and apolymer sheath is secured to the distal tip. Moreover, such a guidewirecan be partially or completely coated with a lubricious or hydrophiliccoating as described hereinabove.

FIGS. 10–13 illustrate further embodiments of the invention in which adistal tip is partially formed, is attached to a core wire and isfurther processed to achieve its final desired shape.

FIGS. 10–11 illustrate a core wire 112 that includes a proximal constantdiameter section 114, a proximal taper section 116, an intermediateconstant diameter section 118, an intermediate taper section 120, adistal constant diameter section 122, a distal taper section 124 and aheat sink portion 126 having a distal end 127. The core wire 112 can bemanufactured from any suitable metal or metal alloy, as discussedpreviously.

In FIG. 10, a distal sleeve 128 having a distal end 130 and a proximalend 132 is positioned proximate the distal end 127 of the heat sinkportion 126 and in some embodiments the distal end 130 of the distalsleeve 128 can extend distally beyond the distal end 127 of the heatsink portion 126. The distal sleeve 128 can be attached or connected tothe core wire 112 using any suitable technique, for example, thosedescribed above. The distal sleeve 128 can be manufactured from anysuitable metal or metal alloy, as discussed previously.

A metal ball 134 (see FIG. 10) can be positioned proximate the distalend 130 of the distal sleeve 128. In some embodiments the metal ball 134can be in contact with the distal end 127 of the heat sink portion 126while in other embodiments the metal ball 134 is held away from the heatsink portion 126 by the distal sleeve 128. The metal ball 134 can beformed of any suitable material, including metals and metal alloys. Insome embodiments, it can be beneficial but not necessary for the metalball 134 to be formed of the same material as the distal sleeve 128.

In some embodiments, the metal ball 134 can be formed from a non-fusibleshape such as a sphere or ovoid that has been coated with a fusiblealloy such as solder. Such a metal ball 134 can be secured by re-flowingthe solder. In some embodiments, the solder could be a bismuthcomposition as described previously. It is contemplated that the metalball 134 itself could be formed from a bismuth fusible alloy.

A coil 136 having a distal end 138 and a proximal end 140 can bepositioned over the core wire 112 such that the distal end 138 of thecoil 136 is positioned proximate the distal end 130 of the distal sleeve128 and that the proximal end 140 of the coil 136 is positionedproximate the proximal taper section 116. The coil 136 can bemanufactured in accordance with the materials and parameters discussedpreviously.

FIG. 11 shows an atraumatic distal cap 142 that has been formed as aresult of at least partially melting the metal ball 134 and the distalsleeve 128. The metal ball 134 and the distal sleeve 128 can be at leastpartially melted using a variety of techniques. In some embodiments, themetal ball 134 and the distal sleeve 128 can be partially melted using awelding process, such as laser welding or plasma welding. In someembodiments (not illustrated), it is contemplated that the distal end138 of the coil 136 and even the distal end 127 of the heat sink portion126 may also partially melt to form a portion of the atraumatic distalcap 142.

In the embodiment shown in FIGS. 10–11, it is to be understood that sucha guidewire can include one or more polymeric layers as discussedpreviously and does not necessarily include a coil, especially if theguidewire has a polymer tip. Moreover, such a guidewire can be partiallyor completely coated with a lubricious or hydrophilic coating asdescribed hereinabove.

FIGS. 12 and 13 illustrate a core wire 144 that includes a proximalconstant diameter section 146, a proximal taper section 148, anintermediate constant diameter section 150, a distal taper section 152and a distal constant diameter section 154 having a distal end 156. Thecore wire 144 can be manufactured from any suitable metal or metalalloy, as discussed previously.

In FIG. 12, a preformed distal cap blank 164 has been positioned overthe distal end 156 of the distal constant diameter section 154. Thedistal cap blank 164 can be formed of any suitable material, includingthe metals and metal alloys discussed with respect to other embodimentsof the invention. In some embodiments, the distal cap blank 164 caninclude an aperture 166 that has been formed in a proximal end 165 ofthe distal cap blank 164. As illustrated, the distal cap blank 164 has adistal end 163 having a squared-off profile. In other embodiments, thedistal cap blank 164 can be formed having a hemispherical or otherwisecurved distal end 163.

A coil 158 having a distal end 160 and a proximal end 162 can bepositioned over the core wire 144 such that the distal end 160 of thecoil 158 is positioned proximate the distal end 163 of the distal capblank 164 and that the proximal end 162 of the coil 158 is positionedproximate the proximal taper section 148. The coil 158 can bemanufactured in accordance with the materials and parameters discussedpreviously.

FIG. 13 shows an atraumatic distal cap 168 that has been formed as aresult of at least partially melting the distal cap blank 164. In someembodiments (not illustrated), it is contemplated that the distal end160 of the coil 158 may also partially melt to form a portion of theatraumatic distal cap 168.

In the embodiments shown, it is to be understood that such a guidewirecan include one or more polymeric layers as discussed previously.Moreover, such a guidewire can be partially or completely coated with alubricious or hydrophilic coating as described hereinabove.

FIG. 14 is an exploded view of some of the components of another examplemedical device 170, which is similar to the other devices describedherein. Device 170 may include a core wire 172 and a distal cap 174.Core wire 172 can be manufactured from any suitable materials includingthose described herein. For example, core wire 172 may include a metal(such as stainless steel, nickel-titanium alloy, etc.), polymer,metalpolymer composite, and the like. In at least some embodiments, corewire 172 may include a proximal section 176, a distal section 178, andan enlarged distal end section 180. Additionally, distal section 178 mayinclude a ribbon 177 formed in the wire 172 or otherwise disposedbetween enlarged distal section 180 and distal section 178. Proximalsection 176 may be similar to other proximal core wire sectionsdescribed herein. For example, proximal section 176 may be configured tobe sufficiently stiff to provide device 170 with the desired level ofpushability and torquability. Similarly, tapered distal section 178 maybe tapered, for example, in order to increase the distal flexibility ofdevice. Enlarged distal end section 180 may be configured to attach todistal cap 174 as described in more detail below. In some embodiments, aribbon can be formed or otherwise disposed adjacent cap 174 and corewire 172. For example, the ribbon may be disposed behind cap 174.

Distal cap 174 may include a tubular body portion 182 and a generallyatraumatic tip portion 184. In some embodiments, body portion 182 maycomprise a hypodermic tube made of a suitable material. Some examples ofsuitable materials include stainless steel, nickel-titanium alloy,nickel-chromium alloys such inconel (including inconel 625), or anyother suitable material including any of those described herein. Tipportion 184 may include a solder ball or other suitable structure thatcan be coupled to body portion 182. Tip portion 184 can be coupled tobody portion 182 in any suitable manner. For example, tip portion 184can be soldered, welded (including plasma, laser, and other knownwelding techniques), thermal bonding, chemical bonding, adhesivebonding, mechanical bonding, frictional fitting, and the like. Distalcap 174 can be formed prior to attachment to core wire 172.

Distal cap 174 may be coupled to core wire 172 as shown in FIG. 15. Inat least some embodiments, body portion 182 of distal cap 174 can bedisposed over enlarged distal end section 180. According thisembodiment, enlarged distal end section 180 may be sized to fit withintubular body portion 182. Cap 174 can be coupled, attached, or otherwisesecured to core wire 172 in essentially any known way including thoselisted above. For example, distal end section 180 and body portion 182can be coupled by laser welding. In this and other embodiments thatinclude the use of thermal energy or otherwise including heat, enlargeddistal end section 180 may act as a heat sink to help absorb anddistribute the heat generated by the coupling process. This may helpreduce the possibility that heat could damage core wire 172.

A covering or sheath 186 may be disposed over a portion of core wire 172and/or cap 174 as shown in FIG. 16. Similar to what is described above,sheath 186 may be made of essentially any appropriate material includingsuitable polymers and the like. In some embodiments, sheath 186 may bedisposed, over tapered distal section 178 and extend distally to definea generally rounded tip for device 170. Additionally, sheath 178 mayextend proximally toward proximal section 176.

Another example medical device 270 is illustrated in FIG. 17. Device 270is similar to device 170, except that covering 286 may comprise a springtip that includes a coil 286. Coil 286 may be made from suitablematerials including those listed herein and may extend, for example,distally from an attachment point adjacent proximal section 176 overdistal section 178. The configuration of coil 286 may vary. For example,coil 286 may have essentially any appropriate shape, thickness, length,pitch, material composition, and the like including any of the variousproperties and configurations described herein.

Distal cap 274 may include tip portion 284. In some embodiments, tipportion 284 may be larger than tip portion 184 (as shown in FIGS. 14–16)so that it has a width or outside diameter that is greater than bodyportion 282. According to this embodiment, tip portion 284 may extendlaterally beyond body portion 282 and define a shoulder region 290.Attaching cap 274 to core wire 172, thus, may include configuring coil286 so that it extends over body portion 282 and terminates adjacentshould region 290. This can occur by configuring coil 286 prior to,during, or after attaching cap 274 to core wire 172. Alternatively, tipportion 284 can be attached to coil 286 and body portion 282 aftercoupling cap 274 to enlarged section 180.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. The scope of the invention is, of course, defined in thelanguage in which the appended claims are expressed.

1. An elongate medical device comprising: an elongate shaft having adistal end and a proximal end; a distal cap comprising a metallichypotube body portion having a distal end and a proximal end anddefining a lumen extending there through, the distal cap furtherincluding a distal tip portion attached to the distal end of thehypotube body portion; wherein the distal end of the elongate shaftextends into the lumen and is attached to the distal cap; and a sheathdisposed about at least the metallic hypotube body portion of the distalcap.
 2. The elongate medical device of claim 1, wherein the distal capis secured to the distal end of the elongate shaft via welding.
 3. Theelongate medical device of claim 2, wherein the distal cap is laserwelded or plasma welded to the distal end of the elongate shaft.
 4. Theelongate medical device of claim 1, wherein the distal cap comprises ametallic material that is welding-compatible with the elongate shaft,also comprising a metallic material.
 5. The elongate medical device ofclaim 1, wherein the proximal end of the distal cap has a substantiallycylindrical outer profile and an inner profile that mirrors an outerprofile of the distal end of the elongate shaft.
 6. The elongate medicaldevice of claim 1, wherein the distal tip portion of the distal capincludes an atraumatic distal surface.
 7. The elongate medical device ofclaim 1, wherein the distal tip portion of the distal cap has ahemispherical profile.
 8. The elongate medical device of claim 1,wherein the lumen in the hypotube body portion of the distal cap isadapted and configured to fit tightly over the distal end of theelongate shaft.
 9. The elongate medical device of claim 1, wherein theelongate medical device comprises a guidewire.
 10. The elongate medicaldevice of claim 1, wherein the sheath comprises a polymer sleeve.
 11. Aguidewire produced by a process of: providing a core wire having adistal end and a proximal end; forming a distal cap comprising ametallic hypotube body portion having a distal end and a proximal end,the proximal end of the hypotube configured to accept the distal end ofthe core wire, the distal cap further including a distal tip portionattached to the distal end of the hypotube; positioning the distal capover the distal end of the core wire by inserting the distal end of thecore wire into the proximal end of the hypotube; attaching the distalcap to the distal end of the core wire; and disposing a sheath about atleast the metallic hypotube body portion of the distal cap.
 12. Theguidewire of claim 11, wherein welding the distal cap comprises laserwelding or plasma welding.
 13. The guidewire of claim 11, wherein thedistal cap comprises a metallic material that is welding-compatible withthe core wire, also comprising a metallic material.
 14. The guidewire ofclaim 11, wherein the sheath comprises a coil.
 15. The guidewire ofclaim 11, wherein the sheath comprises a polymer sleeve.
 16. A guidewirecomprising: a core wire having a distal end and a proximal end; a distalcap comprising a metallic hypotube body portion having a distal end anda proximal end and defining a lumen extending there through, the distalcap further including a distal rip portion attached to the distal end ofthe hypotube; wherein the distal end of the core wire extends into thelumen of the hypotube, and is attached to the hypotube; and a sheathdisposed about at least the metallic hypotube body portion of the distalcap.
 17. The guidewire of claim 16, wherein the distal cap is laserwelded or plasma welded to the distal end of the core wire.
 18. Theguidewire of claim 17, wherein the distal cap and the core wire areformed of welding-compatible metallic materials.
 19. The guidewire ofclaim 16, wherein the proximal end of the distal cap has a substantiallycylindrical outer profile and an inner profile that mirrors an outerprofile of the distal end of the core wire.
 20. The guidewire of claim16, wherein the distal tip portion of the distal cap is adapted andconfigured to provide an atraumatic tip to the guidewire.
 21. Theguidewire of claim 16, wherein the distal tip portion of the distal caphas a hemispherical profile.
 22. The guidewire of claim 16, wherein thehypotube body portion of the distal cap is adapted and configured to fittightly over the distal end of the core wire.
 23. The guidewire of claim16, wherein the core wire comprises a proximal portion having a firstdiameter, an intermediate portion having a second diameter that is lessthan the first diameter, and a distal ribbon portion.
 24. The guidewireof claim 23, further comprising a proximal transition region positionedbetween the proximal portion and the intermediate portion and a distaltransition region positioned between the intermediate portion and thedistal portion.
 25. The guidewire of claim 16, wherein the sheathcomprises a coil having a distal end and a proximal end.
 26. Theguidewire of claim 16, wherein the sheath comprises a polymeric sleeve.27. The guidewire of claim 23, wherein the core wire further comprises adistal heat sink portion that is positioned distal of the distal ribbonportion.
 28. The guidewire of claim 27, wherein the proximal end of thedistal cap is adapted and configured to fit tightly over a distal end ofthe distal heat sink portion and extends proximally to an intermediateposition on the distal heat sink portion.
 29. A guidewire comprising: acore wire having a distal end and a proximal end; a sleeve of metallicmaterial disposed on and secured to the distal end of the core wise; anda distal cap disposed about and attached to the sleeve of metallicmaterial, the distal cap having a distal end and a proximal end theproximal end of the cap including a metallic tubular structure defininga lumen into which the sleeve of metallic material is disposed, thedistal end of the cap including a metallic member attached to thetubular structure defining an arcuate atraumatic surface; wherein thedistal cap is attached to the sleeve such that the sleeve is positionedbetween the distal end of the core wise and an inner surface of thedistal cap.